Southern Hemisphere atmospheric circulation: impacts on Antarctic climate and reconstructions from Antarctic ice core data
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Southern Hemisphere atmospheric circulation: impacts on Antarctic climate and reconstructions from Antarctic ice core data

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Presentation given at the PAGES symposium in Chile in October 2010. (NB I gave this talk before O'Donnell et al. was published so I'd probably do it differently now.)

Presentation given at the PAGES symposium in Chile in October 2010. (NB I gave this talk before O'Donnell et al. was published so I'd probably do it differently now.)

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Southern Hemisphere atmospheric circulation: impacts on Antarctic climate and reconstructions from Antarctic ice core data Southern Hemisphere atmospheric circulation: impacts on Antarctic climate and reconstructions from Antarctic ice core data Presentation Transcript

  • Southern Hemisphere atmospheric circulation: impacts on Antarctic climate and reconstructions from Antarctic ice core data Andrew Russell 1 and Glenn McGregor 2 1 Institute for the Environment, Brunel University, UK. 2 School of Geography, Geology and Environmental Science, University of Auckland, New Zealand [email_address]
  • Acknowledgements Scientific Committee, Valdivia PAGES 2010 Gareth Marshall , British Antarctic Survey Rob Mulvaney , British Antarctic Survey
  • Introduction
    • Antarctic temperature trends
    • Impact of atmospheric circulation
    • Atmospheric circulation reconstructions from Antarctic ice core data
  • Antarctic temperature trends
  • Turner et al. (2005) “Antarctic climate change during the last 50 years” International Journal of Climatology 25 , 279-294.
  • Steig et al. (2009) “Warming of the Antarctic ice-sheet surface since the 1957 International Geophysical Year” Nature 457 , 459-462.
  • The impact of atmospheric circulation on Antarctic climate
  • Atmospheric circulation modes
    • Southern Annular Mode (SAM)
    • Semi-Annual Oscillation (SAO)
    • El Ni ñ o-Southern Oscillation (ENSO)
  • Atmospheric circulation modes
    • Southern Annular Mode (SAM)
    • Semi-Annual Oscillation (SAO)
    • El Ni ñ o-Southern Oscillation (ENSO)
  • The Southern Annular Mode http://www.niwa.co.nz
  • The Southern Annular Mode http://www.niwa.co.nz
  • Negative SAM index
  • Positive SAM index
  • Changes in the Southern Annular Mode IPCC (2007)
  • Changes in the Southern Annular Mode Gillett and Thompson (2003) Simulation of recent Southern Hemisphere climate change. Science, 302, 273–275. Thompson and Solomon (2002) Interpretation of recent Southern Hemisphere climate change. Science, 296, 895–899. IPCC (2007) Marshall (2003)
  • Atmospheric circulation reconstructions from Antarctic ice cores
  • Legrand and Kirchner (1988) “Polar atmospheric circulation and chemistry of recent (1957–1983) south polar precipitation” Geophysical Research Letters 15 , 879–882. Winter [Na]
  • Kreutz and Mayewski (1999) “Spatial variability of Antarctic surface snow glaciochemistry: implications for paleoatmospheric circulation reconstruction”. Antarctic Science 11 , 105–118. EOF(Siple Dome) ASL
  • MJJ [Na] Goodwin et al. (2004) “Mid latitude climate variability in the South Indian and South-West Pacific regions since 1300 AD”. Climate Dynamics , 22 , 783–794.
  • MJJ [Na] Goodwin et al. (2004) “Mid latitude climate variability in the South Indian and South-West Pacific regions since 1300 AD”. Climate Dynamics , 22 , 783–794.
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  • Russell et al. (2008) ASL
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  • Questions
    • What are the sources of precipitation for different sites?
    • How reliable are the datasets being used to analyse the recent atmospheric circulation?
    • How trustworthy are ice core based atmospheric circulation reconstructions when analyses of recent circulation regimes are relatively uncertain?
    • What are the mechanisms driving the SAM and how can our understanding of its recent state be improved?
    • What are the sources of aerosol in the ice?
    • What is the relationship between MSA, ENSO and SIE?
    • Is there any evidence of post-depositional migration of species within ice and can such problems be worked with?
    • How reliable is ice core data, particularly if we attempt to look at seasonal timescales?
    • How can we resolve issues caused by the spatial variability of ice core data?
  • Future directions
    • “ Re-analysis” e.g. PAGES 2k
    • Neural network e.g. Reusch et al. (2005)
    • Modelling studies -> circulation reconstructions
  • Summary
    • Antarctica is warming
    • Atmospheric circulation plays a key role
    • Atmospheric circulation reconstructions are becoming more sophisticated – this needs to develop further